1. Field of the Invention
The present invention generally relates to the field of mechanical soil processing means of rotary implements and more particularly, it is concerned with an agricultural maching adapted to perform mechanical processing of the soil under conditions of very high productivity and flexibility insofar as different displacements and working requirements are concerned.
2. The Prior Art
Generally, such machines, commonly called "agricultural hoes" or just "cultivators" are combined, for operation, with agricultural tractors having a weight and power suitable to the dimensions of the machines and from which the machines receive the power necessary for their advancement as well as for rotation of the implements.
An important and substantial improvement in the machines of the prior art and in the agricultural field in general has been made by the Applicant as disclosed in his U.S. Pat. No. 3,779,320 filed on Oct. 29, 1970 and granted on Dec. 18, 1973. The present invention consists of improvements to such art.
The various means, devices and arrangements of such art have enabled mainly processing of the soil to a considerably depth, such as to transform the traditional tillage, that means the actual crushing and airing of superficial clods, into a deep treatment which in practice has shown to equal a combined ploughing and harrowing action which in turn may be combined with other operations, such as for example seeding, superficial and/or deep application of fertilizers and so forth.
Moreover, the technical solutions according to said prior patent have enabled actuation and use of machines provided with hoe assemblies of a great transversal extension, i.e. capable of dealing, in each single "passage", with a large strip of soil because said technical solutions which rationally exploit the propulsive effect derived by the reaction to the forces applied during deep processing of soil, included the use of a motor of great power to drive the hoe assembly while to move forward the machine (even on the road) a motor of relatively small power was used, the whole self-propelled assembly having a power/weight ratio much higher than that of a traditional tractor/cultivator assembly; this ratio being obtained due to the fact that the machine, as mentioned above, comprises two motors only one of which is of great power (and therefore quite heavy), the energy of which is distributed in a processing or hoeing action of the soil and a thrust in a forward direction, respectively. By suitably proportioning the overall weight of the machine, the distribution of weights on the axes of the machine as well as on all the rotary implements processing the soil, and the powers of the two energy sources, it has been possible to obtain very high production outputs and predetermined ranges of conditions of consistency of the soil to be processed and practicability of the soil by the machine (that is, the drag, irrespective of the fact that the thrust necessary to overcome said drag, is due to the reaction to the tilling effect or the power imparted to the bearing wheels).
These recent developments in the field have practically introduced a new and important methodology of cultivation. There is therefore a tendency to extend this methodology and these possibilities of a high production yield, in a range of processes and soil conditions much wider than that obtained with the quipment described and shown in said U.S. Pat. No. 3,779,320.
Such prior art machines however been proved to be unsatisfactory under certain conditions and are subject to several serious limitations. As a matter of fact, the availability of more flexible machines is a long felt want. For example, certain conditions occur in cases of agricultural work, for instance on soil of poor consistency, wet but not compact and actually presenting only a slight resistance to tilling or hoeing, but on which the machine moves with a certain difficulty and in which the bearing wheels sink to a substantial depth. Frequently, there may be situations, even localized ones, in which the drag is quite high and even higher than the one taken up by the assembly of rotating implements. Similar conditions occur also when it is not intended to use the whole power available and the capacity of processing to a certain depth, of the rotary implements, but when it is intended to perform tilling only at a small depth (which requires limited energy) and in such a case it could prove useful to use the excess or at least part of the excess of energy available, in order to increase to a substantial degree the translation speed during operation with exploitation of said high power/weight ratio (reference is made specifically to said prior patent) is suited in a flexible way to the most varying operating conditions.
For example, the power of the driving motor, for advancement of the vehicle, although generally is more than enough to ensure running on the road as well as during agricultural processing of the soil (advancement which as already mentioned, is partially due and usually, mainly due, to the reaction to operation of the implements) in certain cases could prove to be insufficient; for example in cases when it is necessary to negotiate ditches or uneven soils, access ramps to the field where the work has to be performed, and so forth; it could be desirable to apply to the wheels a higher power.
Particular considerations have to be taken into account with regard to the energy distribution to the assembly of rotary implements and wheels respectively, during operation. In fact, it has been found that on consistent soils (which require a considerable amount of energy for actuation of the rotary implements, in view of the drag that said soils offer to cutting, to their breakage into clods and their crushing) and that due to the fact that they are compact before processing, they are easily practicable by the machine (offering a small drag to advancement of the heavy equipment), practically all the energy available may be applied to the rotary implements, the thrust necessary for advancement being supplied, at times even in excess, by operation of the rotary implements themselves.
In order to hypothetically attain these objects and consequently impart to the machine a suitability or flexibility of service such as to extend its working capacity to a much wider range of conditions, the machine should be provided with two motors, each one having a power sufficient to satisfy the maximum "peaks" of drags even exceptionally encountered in the most varied conditions, such motors having obviously-particularly the one used for traction -- an output much lower than the maximum power delivered. It is obvious that a machine modified in such a way cannot offer the advantageous high power/weight ratio featured by the agricultural machines according to the principles disclosed in said U.S. Pat. No. 3,779,320.
Moreover, although the machines actuated according to said principles have shown to be easily controllable in their advancement speed in relation to the angular speed of the rotary implements (that means a good evenness in dividing the soil into clods); the inevitable local variations in drags of the soil to tilling and to practicability of its surface, may lead to certain drawbacks. In fact, since it is practically indispensable to keep the speed of the "main" motor driving the implements, constant (by means of suitable known devices), when an increase or decrease of drag of the soil leads to a corresponding positive or negative variation in the thrust contributing to translation, the bearing wheels take up a smaller or greater amount of power, respectively, from the driving motor. This may result in a variation in the advancement speed, thus altering said relation. The numerous problems to be solved, the difficulties to be overcome and the requirements to be satisfied in this type of machines, inevitably lead, even in the best of conditions, to the provision of machines very heavy and costly, which it is desired to reduce, and of a controllability not very satisfying.